Scintillation detectors are generally used to detect relatively high energy photons, electrons or alpha particles wherein high energy may be 1 KeV or higher, including α-particles or β-particles. It may be appreciated that these photons, electrons or alpha particles may not be easily detected by conventional photodetectors, which may, for example, be sensitive to photons at wavelengths of 200 nm or greater, including 200 nm to 800 nm. A scintillator, or scintillation crystal, ceramic or plastic, absorbs ionizing waves or particles and converts the energy of the waves or particles to a light pulse. The light may be converted to electrons (i.e., an electron current) with a photodetector such as a photodiode, charge coupled detector (CCD) or photomultiplier tube. Scintillation detectors may be used in various industries and applications including medical (e.g., to produce images of internal organs), geophysical (e.g., to measure radioactivity of the earth), inspection (e.g., non-destructive, non-invasive testing), research (e.g., to measure the energy of photons and particles), and health physics (e.g., to monitor waves or particles in the environment as it affects humans).
Scintillation detectors may typically include either a single scintillator or a number of scintillators arranged in a planar array. Many scanning instruments include scintillation detectors that comprise pixilated arrays of scintillators. Arrays may consist of a single row of adjoining scintillator pixels (linear array) or multiple rows and columns of adjoining scintillator pixels (2-D array). Linear and 2-D arrays may include thousands of scintillator pixels and the system may be constructed and arranged so that an emission from each pixel can be individually detected by a photodetector.
Reflectors may be utilized to surround and/or separate individual scintillators to reflect light generated by a scintillator back into the scintillator, increasing the detectable signal. Reflectors may also be utilized to prevent cross-talk between scintillators in an array, i.e., prevent light generated by a scintillator from entering another scintillator in the array. The reflectivity and/or opacity of many materials that may be utilized in a reflector may be affected by the thickness of the reflector material. Generally speaking, the greater the thickness of the reflector material, the greater the opacity and/or reflectance may be. However, relatively thick separators may interfere with measurements, being that a portion of the array may be lost to the cross-sectional area occupied by separators. In addition, the use of specular reflectors, which may be more opaque than diffuse reflectors for a given thickness, may cause total internal reflection, which may substantially trap light generated by the scintillator within the scintillator. Thus, three relatively important reflector characteristics may include relatively limited thickness, relatively high diffuse reflectivity, and relatively high opacity. In many reflectors presently available, only two of the three characteristics may be achieved in combination at desired levels for a given application.